Field of the Invention and Description of the Prior Art
This invention has reference to x-y position measuring devices for use, for example, in character recognition devices used, such as in connection with a writing machine, for example, an autographic register.
Writing machines have been marketed for many years and these have included autographic registers. The autographic register often comprises a casing including a compartment to receive a pack of folded interleaved continuous stationery webs and means to feed the continuous stationery web through the autographic register. The continuous stationery web consists of an uppermost web and one or more underlying copy record webs. Copy material such as, for example, carbon paper is interleaved between the uppermost web and the underlying copy record web or webs in order that data applied to the uppermost web can be reproduced on the underlying record web or webs. The webs are fed over a writing plate whereat the data is written by hand on the webs. Such data can record a business transaction but may record other data. When data has been recorded on the webs, a handle at one side of the machine is operated whereby one form length of the web is fed out of the register and the underlying part or parts are fed into a filing compartment where the webs are filed, refolded and stored. Portable autographic registers have also been marketed. Generally these portable registers comprise a compartment, in which the unused forms are stored, and a writing plate. In such portable registers the continuous stationery webs are pulled out of the storage compartment by hand by the operator over the writing plate and the individual form lengths of the business form continuous web are located in position by means, for example, of a pair of locating pins which engage with locating apertures at the leading end of each form length of the autographic register business form. One example of a portable autographic register is described in British Patent Specification No. 1293677.
It has also been proposed to provide a character recognition device for automatically recognizing characters as they are written. Thus, in the Specification of British Pat. No. 863,431 there is described apparatus for recording that a hand written character has been written on a supporting surface, an electrical circuit to be activated on movement of a writing instrument in writing the character, and means activated by the circuit for recording the written character. This apparatus may be incorporated in an autographic register or other apparatus for receiving hand writing.
The Specification of British Pat. No. 1,310,683 describes apparatus for obtaining signals representative of the co-ordinates of a point including a sheet of resistive material and an electric resistive member normally held out of contact with one another but capable of making temporary contact on an application by use, for example, of a writing implement and in which changeover means are provided to pass a current through the material and number, in alternative directions of right angles to one another, to derive signals representative of the co-ordinate of the point.
In the Specification of application for British Pat. No. 7943987 (European Application for Pat. No. 803045276.9; U.S. Ser. No. 217,130) there is described a character recognition apparatus having a writing pad comprising a pair of sheets normally electrically insulated from one another but adapted to be brought into contact with one another by writing pressure by a writing implement upon the writing pad, an electrical switching circuit to cause current to flow along the pad along two alternative paths, and a recognition circuit to recognize written characters by virtue of the changes in electrical voltage in the alternative paths, characterized in that one of the sheets of the writing pad comprises a central part of high resistivity and having a border of low resistivity so that the voltage gradient along the length of the pad is linear, and the other one of the sheets comprises a layer of conductive material.